<?php
    session_start();
    if( isset($_REQUEST['login']) && $_REQUEST['login']=='x' &&
        isset($_REQUEST['password']) && $_REQUEST['password']=='x'){
        $_SESSION['ADMIN']=true;
    }else{
        $_SESSION['ADMIN']=false;
    }

    if(isset ($_SESSION['ADMIN']) && $_SESSION['ADMIN']==true){
        echo '<script>document.location="users.php";</script>';
    }else{
        echo '<form method="post" action="index.php">
                <label for="login" style="display:inline-block;width:150px">Login</label>
                <input type="text" name="login" id="login" /><br />
                <label for="password" style="display:inline-block;width:150px">Password</label>
                <input type="password" name="password" id="password" /><br />
                <input type="submit" value="send" />
            </form>';
    }
?>